Hydration for sport in hot weather: before, during, after

Running at sunrise, padel after work, a pickleball game at noon: in Da Nang's heat, what you drink around sport matters even more than in a cool gym. Here is a simple plan, based on sports scientists and the NHS.

Why heat changes things

In hot, humid weather your body cools itself by sweating, and you can lose a lot of water and salts in one session. The NHS advises staying in the shade between 11am and 3pm on very hot days and avoiding exercise that makes you hotter. So in the hot months, play early in the morning or in the evening when you can.

Before you play

Start with enough water in your body. The American College of Sports Medicine says that if you need to drink extra, do it at least a few hours before the activity, so your body has time to absorb it. A simple check: pale yellow pee means you are starting well.

While you play

The same guidance says the goal during exercise is to avoid losing more than 2% of your body weight in water, about 1.2kg for a person of 60kg. It also says that in some situations, such as long sessions, drinks with salts (electrolytes) and carbohydrate can work better than water alone.

Know your own sweat

Everyone sweats differently, so the ACSM suggests weighing yourself before and after exercise to see how much you lose. If you are a lot lighter afterwards, drink more next time.

After you play

After exercise, the aim is to replace the water and salts you lost, the ACSM says. After a long session in the heat, coconut water is a natural option: 100g has 250mg of potassium and 105mg of sodium, according to the US Department of Agriculture.

Signs to stop and cool down

Stop and cool down if you feel very tired, dizzy or sick, or have a headache, cramps or a strong thirst. The NHS lists these as signs of heat exhaustion. Move to a cool place, drink water and cool your skin with water; you should feel better within 30 minutes. A very high temperature, hot skin with no sweat, or confusion can mean heatstroke, which is a medical emergency: call 115 in Vietnam.

Before and after sport at Juicy

At Juicy, Juicy Pops are our hydration drinks, made with coconut water and basil seeds, and Juicy Pops Green adds Himalayan salt. After training, a protein shake in the Maintain size (regular, 360ml) has 30g of protein. We are at 529 Tran Hung Dao, An Hai, every day from 8am to 8pm, and the nutrition facts for our juices, smoothies, shots and Juicy Pops are on getjuicy.vn/nutri. For daily water needs, see getjuicy.vn/nutrition/importance-of-hydration.

Sources: American College of Sports Medicine, Position Stand: Exercise and Fluid Replacement (2007); NHS, Heatwave: how to cope in hot weather; NHS, Heat exhaustion and heatstroke; NHS, Dehydration; US Department of Agriculture, FoodData Central (coconut water).